Tuning and switch device



Filed June 15, 1934 INVENTOR Fa4/vz 5 A? BY 1 ATTORNEY Patented Aug. 18, 1936 UNITED S A as TUNING AND SWITCH DEVICE" Franz Saar, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphic m. b. H., Berlin, Germany, a corporation of Germany Application June 13, 1934, Serial No. 730,396 In Germany June 19, 1933 4 Claims.

In battery operated receiver apparatus and in portable broadcast receiving sets of the kind built of late again on a large scale for automobile or similar craft, and which are ordinarily fed from batteries directly or with the intermediary of a converter and batteries, special difficulties arise because the consumption of current of such equipment turns out to be rather high because of the kind of amplifier tubes nowadays employed. As regards the amount of the consumption of current, this is ascertainable by the aid of a simple calculation. Assuming, for instance, afour tube receiver set, it will be seen that alone for the heating of the tubes a current of 0.4 ampere is required. Inasmuch as the current will be mostly supplied from the existing starter batteries, and since these batteries are unable to furnish'the required large currents constantly without the risk of impairment, and since, moreover, some of the arrangements customarily found in modern receiver sets could not be dispensed with without this having an annoying result in the operation of such sets, it is imperative at least to take care that the load will be made as low as feasible.

What is suggested with this end in view according to the invention is to build the dial illumination means in such Way that it is switched in only when operating the tuning knob. What is thus obtained, on the one hand, is that the dial illumination is possible or producible at will, and this is of special importance in battery operated receiver sets and the like, especially the kind mounted in cars, while, on the other hand, running of the dial lamp during the operation of the receiver is avoided.

The single figure of the drawing by way of example shows the construction of such a switching arrangement in schematic form and partly in section.

Numeral i denotes the casing wall or panel of the broadcast receiver set. Sseated upon the shaft 2 are the tuning means which may be the rotor plates l l which interleave between the stator plates I2 of a tuning condenser C in a well known manner and which are actuated by turning the control knob 3. Upon the spindle 4, at one end of which the knob 3 is disposed, a sleeve 5 is fitted upon the opposite end thereof as by a screw Hi. This sleeve has an elongated hole or slot 6 through which a screw 1 is screwed into the spindle 2, and the same thus transmits the rotary motion of the control knob 3 to the tuning means C. Between the two opposite ends of the spindles 2 and 4, inside the sleeve, a spiral spring I is disposed by the action of which the spindles are normally pressed apart. By this arrangement it is feasible to shift the control knob and the shaft 4 attached thereto in an axial direction without causing incidentally a change in the tuning. Incidentally, by means of a circular flange 8 formed on the sleeve 5 a switch contact 9 is closed and opened through which contact current is supplied to the dial illumination lamp l5 from any source such as a battery l6. As shown, the graduated dial l3 may be secured to the shaft 2 so as to indicate the position of the plates of tuning means C and in such position as to be illuminated by dial lamp 15. It will thus be seen that the operator may merely rotate knob 3 to tune the receiver without the dial lamp l5 being lighted or he may depress the knob until flange 8 actuates switch 9 to close the lamp circuit and may then rotate the knob to tune the set while dial I3 is illuminated. After tuning and release of knob 3 by the operator, spring l0 forces it to its outer position simultaneously opening switch 9 and extinguishing the dial lamp.

Having described my invention what I claim as new and desire to secure by Letters Patent is:

1. In an indicating device, the combination of a rotatable tuning device, a dial connected thereto, a rotatable and longitudinally movable control shaft, means mechanically connecting said tuning device and said control shaft for simultaneous rotation in all positions of said control shaft, a source of illumination, a circuit for energizing said source including a movable switch element, means connected to said control shaft arranged to actuate said movable switch element to open said circuit upon longitudinal motion of said control shaft into its outer normal position and spring means under constant compression urging said control shaft into such outer position.

2. In an indicating device, the combination of a rotatable shaft, an adjustable tuning means secured thereto, a dial connected to said shaft, a sleeve surrounding the end of said shaft, connecting means between said sleeve and shaft arranged to permit axial motion of said sleeve on said shaft and to cause rotation of said shaft upon. rotation of said sleeve in all positions thereof, an electric lamp, a circuit for energizing said lamp including a movable switch blade, and

means for selectively rotating said sleeve or moving it axially into engagement with said switch blade.

' 3. In an indicating device, the combination of a rotatable shaft, an adjustable tuning means secured thereto, a dial connected to said shaft, a sleeve surrounding the end of said shaft, con- 2 J Y o 2,051,181

7' necting means between saidsleeve and shaft arranged to permit axial motion of said sleeve on said shaft'and to cause rotation of said shaft upon rotation 'of'said sleeve, a control shaft seated in therother' end'of said sleeve and secured thereto and a compression spring positioned between said 'control shaft and said rotatable Shaf '4. In an indicating device, the combination of a V rotatable shaft a tuning means secured there- "to, a graduated dial connected to said shaft,'a sleeve engaging the end of said shaft, means en- 7 gaging said sleeve and shaft arranged to rotate said shaft upon rotation of said sleeve in all positions of said sleeve and to permit axial motion of said sleeve on said shaft, an electric lamp, a circuit for energizing said lamp including a movable switch blade, said sleeve being provided with a radial extending portionzadapted to engage said switch blade and a shaft provided with a control knob connected to said sleeve.

FRANZ SAAR. 

